This application is based on and incorporates herein by reference Japanese Patent Application No. 2002-261498 filed on Sep. 6, 2002.
The present invention relates to an ignition coil apparatus and an engine using the ignition coil apparatus.
In automotive engines, ignition coils are attached to each cylinder respectively, and are fixed by individual bolts. An ECU and a battery are wired with the ignition coils via each connector one by one. Subsequently, the exposed ignition coils and wiring cords are covered with other member.
However, conventional ignition coil apparatus has many assembly parts, and its assembly work takes much man-power. In order to reduce assembly man-power, it is proposed to integrate plural ignition coils into one piece as an ignition coil apparatus. As shown in FIG. 5, this ignition coil apparatus 51 is structured so that plural ignition coils 52 are arranged in predetermined interval to correspond with each plug hole 5b of an engine head cover 5, and molded integrally on a base plate 53 with resin. The ignition coil apparatus 51 is attached on the head cover 5 so that each ignition coil 52 is inserted into the corresponding plug hole 5b coaxially. The ignition coil apparatus 51 is fixed to the engine by bolts 53d. 
However, the above ignition coil apparatus 51 have to be manufactured precisely so that all center distances between neighboring plug holes 5b (plug hole pitches), and center distances between neighboring coils 52 (coil pitches) exactly match. Otherwise, the integrated ignition coils 52 cannot be inserted coaxially into the corresponding plug holes 5b. Furthermore, when even one ignition coil 52 fails, the entire ignition coil apparatus 51 have to be replaced with another complete set, so repair work costs high.
In view of the foregoing problems, it is an object of the present invention to provide a simply structured ignition coil apparatus which can be attached on an engine without misalignment. Each ignition coil can be easily replaced individually, and electrical connection can be performed easily.
In the present invention, the ignition coil apparatus comprises ignition coils, holders and a base plate. Each ignition coil includes a body portion (coil-body) and a head portion (coil-head). The coil-body is inserted into a corresponding plug hole of the engine head cover. The coil-head, which is on the coil-body, is a larger diametrical unit than the coil-body. The ignition coil is hooked on the holder by its coil-head, and is supported by the holder from downward, and is pressed by a base plate from upward onto a lower engine head cover. The holder hooks on the base plate loosely, restricting the inserted coil-body with play.
The base plate has flat recesses which receive the upper section of the coil-heads. Each recess is larger than the coil-head in diameter. The recessed peripheral surface restricts displacement of the coil-head with clearance. During assembly work, by sliding of the coil-head within the recess, alignment between the ignition coil and the plug hole can be adjusted easily. That is, the manufacturing precision of plug hole pitch can be eased. The ignition coils are adjustable on the base plate, therefore the ignition coils do not have to be mounted on the base plate precisely.
Plural ignition coils and the base plate can be installed on the engine head cover all together. On the contrary, Individual ignition coil can be replaced by detaching of the holder.
A connector on the coil-head can be easily fitted into a connector on the holder. When the holder is set on the coil-head, and is snap-fitted on the base plate, electrical connection is performed at one time.